Dear Aspirant,

Hormones are a group of chemicals which are released in the blood, which are are responsible for various functions of the body by carrying messages to various organs and tissues. They enable multiple processes in the body through a target action mechanism. Binded to the hormones are specific receptors which are located on the cell membrane of the target organ. This leads to a following consequence of a sequence of actions releasing messengers. These messengers, which are the secondary messengers function to communicate messages or information to  important organelles like the nucleus. The internal receptors find themselves lying in the cytoplasm or the cell or inside the nuceloplasm or even the nuclear membrane. The external receptors find themselves inside the lipid layer of the cell membrane.

If the receptor involves protein hormones, the mechanism followed is fixed receptor mechanism. The lipid layer is water soluble which does not allow the hormones to pass, thus they find themselves attached to the extracellular receptors. This is followed by the production of adenyl cyclase enzyme which causes the desired effect.

The mobile receptor action mechanism involves the steroid hormones that aren't soluble in water. The receptors are inside the cell floating in the cytoplasm and move within the membrane. They are made up of fats.

Hope this helps. All the best!